So, my game has been frozen quite frequently lately, causing a drop in ranked games. This happens mainly at the beginning of a day (be it day 2, day 3, day 4, it has no specific). Is it something that's happening in the game? I feel that I am losing many points of rank due to this (I was in 1914 and now I'm about 1870). I am from Brazil so it can be a reson to drop that much?

When the game freezes, it usually means that your client disconnected from the server. Since we have a system, that punishes leavers in ranked games with a higher decrease of the rating, that is the reason why it drops that much.